1. Field of the Invention
The present invention relates to an immersion-type surface treatment tank.
2. Description of Related Art
Japanese Unexamined Patent Application Publication No. 2002-235197 discloses a technique for performing electrodeposition coating in an electrodeposition tank filled with an electrodeposition paint. In electrodeposition coating, it is necessary to agitate the electrodeposition paint constantly because electrodeposition paint particles are liable to settle out. The agitation of the electrodeposition paint is achieved by a swirl flow.
The electrodeposition tank disclosed in Japanese Unexamined Patent Application Publication No. 2002-235197 described above is formed in an elongated shape so that a plurality of objects to be treated can be immersed simultaneously, which is advantageous from the viewpoint of productivity. If a swirl flow is formed in such an elongated electrodeposition tank, the flow is likely to be turbulent and a lot of energy is required to obtain a predetermined flow rate.
It is an object of the present invention to provide a technique for forming a horizontal swirl flow with less energy in a single tank internal space having an elongated shape in a plan view.